The present invention relates to vehicle seats fitted with pivot mechanisms.
More specifically, the invention relates to a vehicle seat comprising:
first and second seat elements mounted so as to pivot relative to one another about an axis of rotation,
at least one pivot mechanism which comprises a locking device which can be displaced, on the one hand, between a locked position preventing any relative pivoting movement between the first and second seat elements, and, on the other hand, a position that allows a free pivoting movement between the first and second seat elements, this locking device being controlled by a first operating member which can be operated (directly or otherwise) by a user, this first operating member being biased towards a non-operating position in which said first operating member places the locking device in its locked position, and the first operating member being displaceable in an angular operating direction towards an operating position in which said first operating member places the locking device in its unlocked position, the non-operating and activating positions of the first operating member being fixed relative to the first seat element,
and an indexing mechanism which is displaceable between, on the one hand, a non-operating position in which said indexing mechanism is designed so as not impair the relative pivoting movement of the first and second seat elements and, on the other hand, an operating position in which said indexing mechanism is designed to:
allow the second seat element to pivot freely relative to the first seat element, in a first angular direction from the last position of relative adjustment of these two seat elements,
then allow the second seat element to pivot freely relative to the first seat element, in a second angular direction opposite the first angular direction, as far as said last position of relative adjustment of these two seat elements,
the indexing mechanism being controlled by a second operating member which can be operated (directly or otherwise) by a user, this second operating member being biased towards a non-operating position in which said second operating member places the indexing mechanism in its non-operating position, and the second operating member being displaceable into an operating position in which said second operating member places the indexing mechanism in its operating position.
Document EP-A-0 694 434 describes a seat of this type, which is designed to be fitted in the front passenger area of vehicles with two side doors and in which the first and second seat elements are the seat part and the backrest of the seat.
This seat known from the prior art is fitted with a pivot mechanism having toothed plates which incorporate the indexing mechanism allowing:
the position of the backrest of the seat to be adjusted,
and, in order to gain access to the rear seats of the vehicle for example, the backrest of the seat to be pivoted forward and then automatically re-locked in the position previously adjusted by the user.
The pivot mechanism of this known seat has first and second side plates and toothed plates which are slidably mounted relative to the first side plate and which move so as to engage with a bearing plate which is in turn mobile relative to the second side plate, being joined to this second side plate by means of other toothed plates.
In this case, the two side plates of the pivot mechanism are joined to one another by means of two stages of toothed plates, which tends to reduce the strength of the pivot mechanism or makes it necessary to increase the weight and the cost of this mechanism in order to obtain a high mechanical strength.
Furthermore, the pivot mechanism is a specific mechanism and is produced in quite small batches, making it relatively expensive as compared with a standard pivot mechanism.
The objective of the present invention is to overcome these disadvantages.
To this end, the invention proposes a seat of the type in question, wherein:
the locking mechanism provides a link between the first and second seat elements independently of the indexing mechanism,
the indexing mechanism comprises:
an indexing plate not belonging to the locking mechanism, this indexing plate being mounted so as to pivot freely about the axis of rotation independently of the first and second seat elements,
a first checking member not belonging to the locking mechanism, this first checking member being linked to the second operating member and to the first seat element so that it can be displaced relative to said first seat element following the second operating member, this first checking member co-operating with the indexing plate in order to lock it relative to the first seat element when the second operating member is in its non-operating position, and the first checking member allowing the indexing plate to pivot freely relative to the first seat element about the axis of rotation when said second operating member is in its operating position,
and a second checking member not belonging to the locking mechanism, this second checking member being linked to the second operating member and to the second seat element so that it can be displaced relative to the second seat element following the second operating member, said second checking member co-operating with the indexing plate in order to lock it relative to the second seat element when the second operating member is in its operating position, and the second checking member allow the indexing plate to pivot freely about the axis of rotation relative to the second seat element when the second operating member is in its non-operating position,
and, in their non-operating position, the first and second operating members are linked to one another by a lost motion mechanical link which is designed:
to leave the second operating member in its non-operating position when the first operating member is acted on by displacing it into its operating position,
and to drive the first operating member from its non-operating position into its operating position when the second operating member is acted on by displacing it from its non-operating position to its operating position.
As a result of these features, when the user of the seat wants to adjust the inclination of the second seat element (for instance the backrest) in order to make himself more comfortable, he operates the first operating member, which releases the pivot mechanism.
Due to the mechanical link providing a lost motion between the first and second operating members and in view of the fact that the two operating members have fixed non-operating and operating positions relative to the same seat element, the second operating element will remain in its non-operating position so that the indexing mechanism is in turn in its non-operating position and does not impair the relative pivoting movement of the first and second seat elements.
On the other hand, when the user of the seat wants to pivot the second seat element rapidly in the first angular direction (when this is the backrest for example, in order to fold this backrest as far forward as possible) he acts on the second operating member, which not only releases the pivot mechanism but also allows the indexing mechanism to shift into its indexing position, restricting the relative pivoting movement of the first and second seat elements so that the second seat element finally returns to its initial position relative to the first seat element.
It should be pointed out that the pivot mechanism of the seat proposed by the invention may be of any standard construction, which means in particular that the same pivot mechanisms can be used for substantially all types of seat which have a backrest which allows the user to act directly on said backrest, regardless of whether this backrest can be folded down towards the front or not in order to gain access to the rear seats of the vehicle.
As a result of this standardization option, the invention brings gains in terms of high productivity and thus an overall reduction in the cost of the seats.
Furthermore, the invention does not require this pivot mechanism to have two stages of bearing plates, enabling a first pivot mechanism to be used which is simple and strong. In any event, the strength of the first pivot mechanism is not dependent on the presence or otherwise of the indexing mechanism.
In preferred embodiments of the invention, one and/or the other of the following features may also be incorporated:
the indexing plate comprises:
an indentation in which the first checking member locates when said first checking member is locked in its non-operating position,
and a circular guide surface centered on the axis of rotation, on which the first checking member slidably bears when the indexing mechanism is in its operating position and the second seat element has been displaced in the first angular direction relative to the first seat element from the last position of relative adjustment;
the indexing plate also has a stop which is adjacent to the indentation of said indexing plate and which is disposed in the first angular direction relative to said indentation, in order to allow a pivoting movement of the second seat element relative to the first seat element only in said first angular direction from said last position of relative adjustment of these two seat elements when the indexing mechanism is in its operating position, and then to check the relative pivoting movement between the first and second seat elements in the second angular direction when the first seat element has been returned to its last position of adjustment relative to the second seat element;
the first checking member is a hook joined to an operating lever which constitutes the second operating lever and which is mounted on the first seat element so as to pivot about an axis parallel with said axis of rotation, the indentation and the guide surface of the indexing plate being radially oriented towards the exterior relative to the axis of rotation;
the first operating member is mounted so as to pivot about the axis of rotation and is joined to an operating lever which is in turn pivotally mounted on a connecting rod joined to the operating lever with some play, the non-operating positions of the first operating member and the operating lever being such that said play is picked up in a direction corresponding to the displacement of the operating lever from its non-operating position to its operating position when the indexing mechanism is in its non-operating position;
the second checking member is coupled with the operating lever by a coupling member pivotally joined to said operating lever (by a pivot, strictly speaking, or by any other linkage means that will allow a certain degree of flexibility, including hooking a flexible cable) at a fixing point which is located substantially on the axis of rotation when the indexing mechanism is in its non-operating position;
the operating lever is joined to a manual operating member which is accessible to a user by means of a coupling member which is in turn pivotally linked to said operating member (by a pivot, strictly speaking, or by any other linkage means that will allow a certain degree of flexibility, including hooking a flexible cable) at a fixing point which is located substantially on the axis of rotation when the indexing mechanism is in its non-operating position;
the second checking member is an indexing bearing plate controlled by a cam mechanically coupled with the second operating member, this cam being mounted on the second seat element so as to pivot about a pivot axis parallel with said axis of rotation, said cam having a circular operating surface centered on said pivot axis, which operating surface holds the indexing bearing plate locked against the indexing plate within a certain angular pivoting range of the cam when the second operating member is in its operating position;
the second checking member is directly coupled with the second operating member by a resilient link;
the first and second seat elements are a seat part and a backrest respectively.